The invention relates to a 
spinning product on-line 
quality monitoring method based on the computer graphical recognition principle, which adopts a 
digital image collector fixedly arranged at a 
discharge port of a 
machine relating to a plurality of processes of cotton 
carding, drawing and roving in the 
spinning production process, a lens thereof faces the semi-finished products to take photographs of the semi-finished products during cotton 
carding, drawing and roving according to a photographing frequency stated in one 
unit of time, the collected linear or 
planar array digital pictures are delivered in real time to a main spot processor which is equipped with a standard 
library and a defect 
library for judging defects of the semi-finished products, one a defect is detected, the main spot processor transmits a warning 
signal or even stops the 
machine station, and reports the defect type, calculates and indicates the specific location where the defect occurs. The on-line 
quality monitoring method can be adopted to conduct non-stop inspection of the semi-finished products in the running process of equipment, so as to judge defects of products and indicate the defect types and locations of defects.